The agency says the firefighters should have been given a better picture of the location of the blaze. And commanders on the field, the report stated, should have assumed a worst-case scenario once it failed to get a radio response from them.

The San Francisco Fire Department originally cited the deaths as accidental. The department also completed an investigation a few months back finding excessive heat may have damaged radio equipment.

The department now has several recommendations to quickly find firefighters who do not respond.